FeS clusters in mitochondrial complex I and their corresponding
EPR signals. The FeS cluster arrangement is from the structure of
the hydrophilic arm of complex I from T. thermophilus;5 the “N7” cluster (non-conserved)
has been deleted. The clusters are named according to their cluster
type and subunit location in B. taurus complex I
(black), and the EPR signals (N1b, N2, N3, N4, and N5, red) that are
exhibited by the NADH-reduced mitochondrial enzyme are indicated next
to the clusters that they have been assigned to;9,11 clusters
in gray do not contribute to the EPR spectrum of NADH-reduced mitochondrial
complex I. The distances between the clusters are the distances between
the centers of the two closest atoms.